As a non-contact power supply system, a system like the one described in FIG. 1 of Patent Document 1 is known. When examining the system described in Patent Document 1, the present inventors first created a diagram for examination based on FIG. 1 of Patent Document 1. The diagram for examination created is FIG. 7. Using FIG. 7, an explanation of the non-contact power supply system is made below.
The non-contact power supply system depicted in FIG. 7 includes an electricity transmitting device 701 which is provided on the side of an electric power provider such as railroad stations, stores, etc. and a portable electronic device 702 that a user has. A high-speed, large-capacity electricity storage module 720 provided in the portable electronic device 702 is charged in a contactless manner by the electricity transmitting device 701. Thus, the electricity transmitting device 701 can also be regarded as a non-contact charging device.
The electricity transmitting device 701 includes a non-contact type processing module 713 such as an NFC (Near Field Communication) reader, a non-contact type electricity transmission module 712, and an electricity transmission control module 711. The portable electronic device 702 (hereinafter also referred to as a portable terminal device or portable terminal) 702 includes a non-contact type processing module 723 for non-contact type processing operation such as NFC, a non-contact type electricity transmission module 722 for charging, an electricity transmission control module 721 which performs charging judgment and control, and a large-capacity electricity storage module 720 which can be charged at high speed.
A user who owns the portable terminal 702 brings the portable terminal 702 close to the electricity transmitting device 701; by this action, electronic payment or the like is performed. By this action, data transmission (authentication, read/write, etc.) is performed between the non-contact type processing module 713 present in the electricity transmitting device 701 and the non-contact type processing module 723 present in the portable terminal 702 and electronic payment or the like is implemented. On the other hand, by this action, electric power is transmitted in a contactless manner from the non-contact type electricity transmission module 712 present in the electricity transmitting device 701 to the non-contact type electricity transmission module 722 of the portable terminal side. The non-contact type electricity transmission module 722 rectifies received electric power and charges the high-speed, large-capacity electricity storage module 720 with the electric power. The electricity transmission control modules 711, 721 in FIG. 7 perform control of contactless electricity transmission between these modules and charging control for charging the high-speed, large-capacity electricity storage module 720.
In the system of FIG. 7, because the power supply (high-speed, large-capacity electricity storage module 720) of the portable terminal 702 is charged while data transmission (communication) is performed between the non-contact type processing modules 713 and 723, it would become possible to reduce time for charging the portable terminal 702. Especially, if communication between non-contact type processing modules 713 and 723 is frequently performed, the portable terminal 702 can be used continuously without being charged.
Communication and electricity transmission for charging in a contactless manner, depicted in FIG. 7, are implemented in a relatively close range such that distance between the electricity transmitting device 701 and the portable terminal 702 is several centimeters or shorter. Transmission in such a close range is generally based on transmission by magnetic coupling (electromagnetic coupling) such as an electromagnetic induction method and a magnetic resonance method. This is for the following reason: given that, for example, transmission via radio waves is applied, degradation of energy being transmitted is inversely proportional to distance r in the case of transmission via radio waves, whereas degradation of energy being transmitted by electromagnetic coupling is inversely proportional to the square of transmission distance r. Hence, for example, if transmission distance is shorter than 1 m, term 1/(r2) will be larger than 1/r; therefore, the shorter the transmission distance, transmission by electromagnetic coupling is more advantageous.
A range of frequencies from 100 kHz to ten and several MHz order is used for communication and electricity transmission for charging in a contactless manner. As an antenna for transmitting/receiving these frequencies, an antenna having the shape of a coil with turns ranging from several turns to on the order of several tens of turns is generally used in order to strengthen magnetic coupling and enhance transmission efficiency. As an antenna for use in the portable terminal depicted in FIG. 7 for contactless communication and electricity transmission in a contactless manner, a small coil-shaped antenna with a diameter of on the order of 4 cm which can be built in the terminal housing is used (refer to, e.g., Non-Patent Document 1).